Control device



April 6, 1943.,

III

E. H. AYERS 2,315,918

CONTROL DEVICE Filed April 50, L942 Fig.1.

mum llnum 48 Inventor:

Ed av H. Ayers, l8

H'is 'Attorheg.

Patented Apr. 6,-1943 2,315,918 CONTROL DEVICE Edgar H. Ayers, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application April 30, 1942, Serial No. 441,148

7 Claims. '(Cl. 200--83) My invention relates to control devices, more particularly to temperature responsive control devices for controlling the circuit of a driving motor such as in an electric refrigerator and has for its object a simple, reliable and low cost control device.

In carrying out my invention in one form, I arrange the bellows spring in direct opposition to the temperature responsive bellows with a movement of the switch'arm, I provide a stop against which normally rests the side of the operating member opposite the operating projection, .and I also arrange the seat for the As shown, the various parts are mounted on a supporting base l'I which is provided with a cylindrical recess l8 for the bellows Hi, this recess being deep enough so that the bellows projects only a short distance above the upper surface of the support II where the bellows engages the operating member l2.

Secured to the upper surface of the support I! is an inverted U-shaped supporting member I! made of a suitable metal such as steel, the ends of its legs being secured to the support H by screws and 2|. One leg of the member I9 is provided with a vertically extending slot 22 into which extends'l'oosely a projection 23 on the support i2. The other leg of the support i9 is provided with a short section 24 extending vertically and of reduced width which is embraced loosely by the operating projection I3 and a shorter positioning projection 25 on the operspring slightly higher on this side so that the operating member is normally held against the tion of the switch arm.

For a more complete understanding of my in-' .ating member l2. Thus the operating member i2 is free to move, upward, as seen in the drawing, until the projection 23 engages the upper wall of the slot 22 and the projections i3 and 25 engage the shoulders marking the upper termination of the reduced portion 24. The member I2 has suificient freedom of movement on vention, reference should be had to the accompanying drawing in which Fig. 1 is a side view of a control device for electric refrigerators embodying my invention; Fig. 2 isan end view of the operation of the switch arm I4.

with the cover in section; Fig. 6 is a fragmentary view showing the supporting frame for the bellows operating parts; while Figs. '1 and 8 are views showing details of construction.

Referring to the drawing, in one form of my invention 1 provide a temperature responsive expansible bellows lflc which is cylindricalwith peripheral corrugations and a helical loading center line coincident with the center line of the bellows l0. Between the spring and the bellows is an operating member [2 whose lower side forms aseat for the upper end of the bellows and whose upper side is provided with a circular recess forming a seat for the spring H. A laterally extending projection lion the operatingmemthe support IS in adownward direction to assure As shown in Fig. 6,'the inverted U -shaped supporting member i9 has secured to it a second .u shaped supporting member 26, the two U-shaped members l9 and 26 forming together a rectangular metallic frame or support. The

' ends of the two members are turned outward and secured together by welded joints 2'! and 28, these outwardly extending portions forming projections which-are secured to-the support H by the screws 20 and 2| whereby the rectangular frame d is secured to the support.

. These two members i9 and 26 are shown clearly in Fig. 6 and form a support for the bellows Hi, operating member l2, spring H and other parts spring H in opposition to the-bellows having its a V directlyassociated therewith. Also, as shown in Fig. 3, the member 26 extends downward into the recess or inverted cap enclosure IS on the lower side of the support i1. As shown, the tube 29 leading to the .bellows is secured by a soldered joint 30 to, thelower end of the member .26; thetube passing through a central aperture ber l2 engages and operates 'a spring switch arm 1 i4, snap action being obtained by a small permanent magnet is and an armature it carried d Y I 56 bythe switch arm.

in the member. It will, be understood that the tubefl29 extends, to the part whosetemperature is thereby controlled, such as the evaporator of the refrigerator, where the vend of the,tube is sealed, and thatthe tube and bellows, form a closed system in which is contained a quantity of fluid or gas whose pressure varies with its temperature whereby the bellows is caused to expand and contract with changes in temperature so as to operate the member l2.

The pressure of the spring ll applied to the operating member l2 can be adjusted by turning a knob 3| having a center line coincident with the center line of the spring H and rotatably mounted in the upper or base portion of the support 19. At its lower end this rod carries a threaded portion 32 which is in screw-threaded engagement with a metal seat 33 for the upper end of the spring II. This seat 33 is held against turning by a pair of projections 34 which embrace one arm of the member l9, as seen in Fig. 5.

For the purpose of latching the contact arm i4 in its open circuit position, a cam projection 35 is provided on the lower face of the knob 3|. It is contemplated that the threaded portion 32 will have suflicient thread pitch to give the desired adjustment in the pressure of the spring I l in less than one revolution of the knob. Also, as shown, the threads will be such as to move the seat 33 downward and compress the spring when the knob is turned counterclockwise, looking down on Fig. 3. Thus, as the knob is turned in a counterclockwise direction, the cam 35 just before the knob reaches its extreme counterclockwise position engages the upper end of a push rod 36, the lower end of which engages the switch arm H. A small amount of continued rotation of the knob causes the cam to iorce this rod 36 downward, thereby moving the arm l4 downward to its open circuit position where it is held as long as the knob remains in this position. This provides for the stopping of the refrigerator as desired, for example, to allow the evaporator to defrost itself.

As shown, the push rod 36, in order to secure it in place, is provided with a short portion 31 on its lower end of reduced size, which portion extends through an aperture 38 (Fig. 4) in the switch arm. As shown also, the push rod is a stra having a rectangular cross-section made of an electrically insulating material. Its upper end slides in a slot 3! in a projection on the upper end of the support IS. The hole 33 in the arm l4 for the push rod 3| is also rectangular in outline and positioned directly below the slot 39 with its longer dimension at right angles with the slot 33. Thus the push rod is put in place by inserting its lower end in the aperture 38 until the reduced portion 31 is in the aperture, then turning the push rod 90 degrees about its longitudinal center line and slipping it sidewise into the slot 39. The upper end of the push rod 36 is further held by the cover 4 which encloses the operating parts and also,-as shown, the upper end of the support II, this cover being provided with an aperture through which the rod 3 extends loosely in the path of the cam 35.

As shown in Fig. 4, the spring contact arm I4 is L-shaped, i. e., it extends from its free end along one dimension of the support l1 and then extends across the end of the support l1 to the support 4| for the switch arm. This support 4| extends downward into engagement with the lower side of the base ll where it is secured to the base by suitable screws (not shown), this portion of the support 4| on the bottom of the base constituting a connection terminal for the switch arm. By thus extending the switcharm 14 along two sides of the base, the advantage of increased length and hence flexibility is obtained,

the dimensions of the base being maintained as small as possible.

A stationary spring switch arm 42 carries a stationary contact 43 in position to be engaged by the contact on the end of the arm l4. This arm 42 is just above the arm l4, as seen in Fig. 3. Its fixed end is secured to a bracket or support 44 secured to the lower side of the base by means of screws 45, this support 44 also constituting a connection terminal for the stationary contact arm. Preferably the contact arm is electrically secured to the support 44 by a spot welded joint 48. For adjustment of the arm 42 the support 44 extends a short distance along the arm 42 but at an angle therewith, and carries an adjustment screw 41 by means of which the position of the arm 42 and of the stationary contact 43 can be adjusted as desired with relation to the movable contact.

This adjustment by the screw 41 varies primarily the temperature differential between the closed and own positions. It varies the cold temperature at which the switch is opened without affecting the higher temperature at which the switch is reclosed. In other words, with the contact 43 in a raised position a lower temperature is required to snap the movable contact arm l4 to its open position.

A screw 48 is provided in the base in position to engage the movable end of the contact arm in its open circuit position. This adjustment changes the high temperature at which the contact arm is moved to its closed position.

During normal operation of the contact arm l4 between its closed and open circuit positions by the bellows whereby the refrigerator is maintained at a predetermined temperature, the projection 23 on the operating member l2 rests continuously on the lower edge of the slot 22 which edge forms a stop. In moving the switch arm, the operating projection l3 on the other end therefore moves about this stop, constituted by the lower edge of the opening 22, as a pivot. Of course in the event of an extremely high bellows temperature as when the refrigerator is shut down by permanently disconnecting it from the electric circuit, the operating member I2 is for ced bodily upward against the spring II, the projection 23 moving to the upper end of the slot 22.

This pivotal movement of the slidable member l2 in operating the contact arm provides the smallest possible temperature differential between the open and closed circuit positions of the switch arm 14. It is essential in the effectin; of this pivotal operation that the force of the spring ll be applied to the operating member l2 at a point between the point of application of the bellows force and the stopiormed by the lower edge of the aperture 22. The spring II and the bellows ll are shown as in axial alignment, that is, having a common center line, but because of manufacturing inaccuracies in the sprin for quantity production, the spring force will not be applied evenly to the operating member l2, and therefore the spring force ordinarily will not directly oppose the bellows force. To assure the application of the spring force between the bellows force and the stop, the corresponding side 49 or the spring seat on the operating memher is made higher than the other side, this high side, in other words, being adjacent the Projection 23. Moreover, in the assembly of the device, the spring II is preferably rotated about its longitudinal center line on the operating member so as to bring the high side of the spring on the high'point 49 of the seat. It will be understood, of course, that the high side of the spring is, in reality, the lowermost side of the spring as seen in the drawing.

While I have shown a particular embodiment of my invention, it will be understood, of course. that I do not wish to be limited thereto, since many modifications may be made and I therefore contemplate by the appended claims to cover any such modifications as fall within true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

l. A control device comprising a rectangular metal frame, an operating member extending across said frame, means securing said operating member to said frame for limited sidewise sliding movement with relation to said frame, a bellows temperature responsive operating device mounted between one side of said operating member and one end of said frame, a compression spring between the other side of said operating member and the other end of said frame, said frame forming a support for said parts and holding said parts together against the force of said spring, means for adjusting the force applied by said spring to said operating member,

and switching means outside of said frame operated by said operating member.

2. A control device comprising a base, a frame secured to said base, a temperature responsive bellows in said frame, an operating member extending across said frame having its ends slidably mounted in said frame, a spring in said frame normally holding said operating member against said bellows, said frame forming a support for said parts and holding said parts together against the force of said spring, means including a screw mounted on said frame for adjusting the force applied by said spring to said operating member, a flexible contact arm outside of said frame mounted on said base adjacent said supporting frame, an operating projection on one side of said operating -member engaging said contact arm so that said contact arm is moved by said bellows in response to changes in temperature, a projection on the opposite side of said operating member, and a stop on said frame for said second projection about which said operating member pivots in operating said contact arm.

3. A control device comprising a base provided with a recess, a rectangular metal frame having a first and inserted in said recess and secured to said base, an operating member extending across said frame in substantially parallel relation with said base, means securing each end of said operating member to said frame for limited sidewise sliding movement with relation to said frame, a bellows temperature responsive operating device mounted between one side of said operating member and said first end of said frame, a compression spring between the other side of said operating member and the other end of sad frame, said frame forming a support for said parts and holding said parts together against the force of said spring, a screw mounted on said frame for adjusting the force applied by said spring to said operating member, a spring contact arm mounted on said base adjacent said frame, an extension on said operating member projecting outside of said frame into engagement with said contact arm-so as to move said contact arm with said bellows,

the

a stationary contact 76 mounted on said base in position to be engaged by said contact arm, and means for giving said contact arm a snap movement from one position to another.

4. A control device comprising a base, a frame secured to said base, a temperature responsive bellows in said frame, an operating member extending across said frame slidably mounted in said frame, a spring in said frame normally holding said operating member against said bellows, said frame forming a support for said parts and holding said parts together against the force of said spring, means including a screw mounted on said frame for adjusting the force applied by said spring to said operating member, a knob on said screw, a flexible contact arm mounted on said base adjacent said supportin frame, an extension on said operating member engaging said contact arm so thatsaid contact arm is moved by said bellows in response to changes in temperature, a projection on said knob, and a member forming an operating connection between said contact arm and said projection so that when said knob is turned to a predetermined position said member is operated by said projection to move said contact arm to a predetermined position.

5; A control device comprising a base, a frame secured to said base, a temperature responsive bellows in said frame, an operating member extending across said frame slidably mounted in said frame, a spring in said frame normally holding said operating member against said bellows, said frame forming a support for said parts and holding said parts together against the force of said spring, means including a screw mounted on said frame for adjusting the force applied by said spring to said operating member, a knob on said screw, a flexible contact arm mounted on said base adjacent said supporting frame, an extension on said operating member engaging said contact arm so that said contact arm is moved by said bellows in response to changes in temperature, a second flexible contact arm mounted adjacent said supporting frame, cooperatin contacts on the movable ends of said contact arms, a projection on said knob, and a member mounted on said supporting frame having one end engaging said first contact arm and its other end in the path of movement of said projection so that when said knob' is turned to a predetermined position said member is operated to move said first contact arm to its opencircuit position and hold it in that position.

6. A control device comprising a base, a frame secured to said base, a temperature responsive bellows in said frame, an operating member slidably mounted in said frame, a spring normally holding said operating member against said bellows, means comprising a screw mounted on said frame for adjusting the force applied by said spring to said operating member, a knob on said screw, a first spring contact arm mounted on said base adjacent said supporting frame, an extension on said operating member engaging said contact arm so that said contact arm is moved by said bellows in response to changes in I cooperating with said magnet so as to snap said .flrst contact arm into and out of circuit 7. A control device comprising a rectangular metal frame, an operating member extending across said frame having its opposite ends slidably mounted in said frame thereby to mount said operating member for limited sliding movement on said frame, one of said ends being elongated to form an. operating projection, a bellows temperature responsive operating device mounted between one side of said operating member and one end of said frame, a compression spring between the other side of said operating member and the other end of said frame, said frame forming a support for said parts and holding said parts together against the force of said spring, a seat on said operating member for said spring having a high portion engaged by one side of said spring between the point of engag'ement of said bellows with said operating member and, the other end of said operating member, and a stop on said frame against which said other end of said operating member'is held normally by said spring so that upon expansion of said bellows in response toan increase in temperaturesaid operating member is moved about said stop as a pivot, and switching means engaged and operated by said operating projection. a

EDGAR H. AYERS. 

